A number of people have pointed to this interesting piece from Saturday's London Telegraph that talks about the lingering animosity some Islamists may feel for Spain:
At the beginning of the 11th century, three quarters of Spain's population was Muslim but, as soon as the Catholic monarchs Ferdinand and Isabella completed the reconquest of the country for Christianity, the Muslims were ordered out.
The humiliation has never been forgotten in the Arab world.
The sense of hurt has grown since Spain, for decades a friend of the Arab world, backed the US-led war on Iraq, despite vast domestic opposition.
A dozen al-Qa'eda-linked suspected terrorists have been arrested in Spain from among its burgeoning community from North Africa.
Bin Laden has identified Spain as a worthy target, and the "settling of old accounts" will send a tingle down many an old Spaniard's spine. Bin Laden gave warning that Spain would be singled out for attack in a taped message released last October through al-Jazeera, the Arab satellite channel.
He said Spain would be among six nations considered "special" targets for its role in the Iraq war. Bin Laden has also spoken of Al-Andalus, regarded with nostalgia by Islamists as the halcyon age of Muslim power and artistic achievement.
Whole thing here.